President Trump kicked off the first foreign policy crisis of his new administration by signing an executive order mandating the construction of the much-promised border wall with Mexico, resulting in as-yet-unresolved confusion as to how the wall will be paid for and an ongoing diplomatic scuffle with Mexican President Enrique Peña Nieto. Benjamin Wittes spoke with Stephanie Leutert, the Mexico Security Initiative Fellow at the University of Texas at Austin and writer of Lawfare's "Beyond the Border" series, to chat about what the wall might look like, how effective it will or won't be, and what this means for U.S.-Mexico relations.